Organic EL display device and method for fabricating the same

ABSTRACT

An organic EL display device and a method for fabricating the same are disclosed, wherein an organic luminescence layer is formed at a crossing region of first and second electrodes using a shadow mask on which a plurality of holes are connected by bridges.

This application is a Continuation of U.S. patent application Ser. No.10/185,012, filed Jul. 1, 2002, now U.S. Pat. No. 6,884,139, and claimsthe benefit of the Korean Application No. 2001-0039542 filed on Jul. 3,2001, which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device, and moreparticularly, to an organic electroluminescence (EL) display device anda method for fabricating the same.

2. Discussion of the Related Art

A method of using a shadow mask as shown in FIG. 1 is the most efficientmethod to improve the luminescence efficiency among methods of formingR, G, and B pixels in fabricating a full-color organic EL displaydevice.

FIGS. 1A to 1D are diagrams showing a related art shadow mask and afull-color organic EL display device according to a pixel array method.

As shown in FIG. 1A, an first electrode 2 is formed on a transparentsubstrate 1 and barriers 7 are additionally formed on the same toseparate between an insulating film 3 and a second electrode.

Also, using a shadow mask 6, a common luminescence layer 5 of R, G, andB, and each of organic luminescence layers 5-1 to 5-3 of R, G, and B isformed at a corresponding pixel on the insulating film 3.

Then, the second electrode is formed on the entire surface.

There are three different types (i.e. a strip type as shown in FIG. 1B,a delta type as shown in FIG. 1C, and an array type as shown in FIG. 1D)in forming an organic luminescence layer using a shadow mask dependingon the array method of a pixel. In the array type, the size of R pixelis designed to be larger than G or B pixel to supplement theluminescence efficiency of the R pixel.

The strip type is best among the above three pixel array types in termsof the aperture ratio and first electrode resistance. In other words,because first electrodes are formed in the form of strips, the devicecan be driven with low driving voltage.

On the other hand, in the strip type, the shadow mask 6 should also bemade in a strip form as shown in FIG. 1. In this instance, problems suchas the transformation or droop of the shadow mask 6 are caused in alarge degree because of an external pulling strength. Accordingly, inthe process of deposition, colors spread not only on the intended pixelregion but also on other areas because of shadow effect.

To obviate the above-mentioned problems, as shown in FIG. 2, a shadowmask on which mask holes are made in turns while having the same pixelarray structure as that of the strip type of FIG. 1B is applied.

FIGS. 2A to 2D are deposition process diagrams of an organicluminescence layer of a full-color organic EL display device using therelated art shadow mask structure.

In this method, however, each organic luminescence layer displaying oneof R, G, and B colors should be formed by carrying out alignment anddeposition twice respectively. That is, to form three layers of R, G,and B, the deposition should be carried out six times in all after thealignment being carried out six times as well.

In other words, to form organic luminescence layers of R, G, and B, incase of using the shadow mask 6 of FIGS. 1B to 1D, the shadow mask isaligned and deposited three times respectively. In case of using ashadow mask shown in FIG. 2, however, the shadow mask should bedeposited 6 times.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an organic EL displaydevice and method for fabricating the same that substantially obviatesone or more problems due to limitations and disadvantages of the relatedart.

An object of the present invention is to provide a full-color organic ELdisplay device and a method for fabricating the same, in which animproved shadow mask structure is provided to prevent a mask patternfrom being transformed, thereby obtaining high luminescence efficiency.

Another object of the present invention is to provide a full-colororganic EL display device and a method for fabricating the same whichhas a shadow mask structure that provides a predetermined number ofbridges formed over a long strip-shaped holes so as to preventtransformation and droop caused by a pulling strength from occurring,thereby obtaining high aperture ratio and low driving voltage.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, afull-color organic EL display device of the present invention includesorganic luminescence layers of R, G, and B formed in a strip shape at aplurality of pixels, which are defined by a crossing region of first andsecond electrodes, on a transparent substrate using a mask which has aplurality of strip-shaped holes and a plurality of bridges crossing theholes.

In the preferred embodiment of the present invention, thin metal thatact as bridges is formed over long strip-shaped holes of a shadow maskso as to prevent the shadow mask from being transformed or droopedbecause of the pulling strength. The organic luminescence layers of R,G, and B are alternately arranged in rows by three times' alignments ofthe shadow mask.

To further achieve these objects and other advantages and in accordancewith the purpose of the invention, as embodied and broadly describedherein, there is provided a mask for fabricating a display device thatincludes a plate having a plurality of holes, and a plurality of bridgesconnecting the holes, wherein the bridges are formed on the same ordifferent plane as the plate.

To further achieve these objects and other advantages and in accordancewith the purpose of the invention, as embodied and broadly describedherein, there is provided a mask for fabricating a display device thatincludes a plate having a plurality of holes, and a plurality of bridgesconnecting the holes, wherein the bridges are formed on the same ordifferent plane as the plate and thicker than the plate.

To further achieve these objects and other advantages and in accordancewith the purpose of the invention, as embodied and broadly describedherein, there is provided a mask for fabricating a display device thatincludes a plate having a plurality of holes, and a plurality of bridgesconnecting the holes, wherein the bridges are formed on the same ordifferent plane as the plate and at the same thickness from that of theplate.

To further achieve these objects and other advantages and in accordancewith the purpose of the invention, as embodied and broadly describedherein, there is provided a mask for fabricating a display device thatincludes a plate having a plurality of holes, and a plurality of bridgesformed between the adjacent holes, wherein the bridges are formed on thesame or different plane as the plate and thicker than the plate.

To further achieve these objects and other advantages and in accordancewith the purpose of the invention, as embodied and broadly describedherein, there is provided a mask for fabricating a display device thatincludes a plate having a plurality of holes, and a plurality of bridgesformed between the adjacent holes, wherein the bridges are formed on thesame or different plane as the plate and at the same thickness from thatof the plate.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIGS. 1A to 1D illustrate diagrams showing full-color organic EL displaydevices in accordance with pixel array types and related art shadowmasks;

FIGS. 2A to 2D illustrate deposition process diagrams of an organicluminescence layer of a full-color organic EL display device using ashadow mask structure of a related art;

FIGS. 3A to 3D illustrate deposition process diagrams of an organicluminescence layer of a full-color organic EL display device using ashadow mask structure of the present invention;

FIG. 4 illustrates a plane view of a shadow mask in accordance with thepresent invention; and

FIGS. 5A to 5C are detailed diagrams showing a part ‘A’ of the shadowmask of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIGS. 3A to 3D illustrate deposition process diagrams of an organicluminescence layer of a full-color organic EL display device using ashadow mask structure of the present invention.

Referring to FIG. 3A, a first electrode 20 of a transparent electrodematerial is formed on a transparent substrate 10. A supplementaryelectrode may be applied to reduce the resistance of the first electrode20. The substrate includes at least thin film transistors.

Metals which have relatively lower resistance than the resistance of thefirst electrode 20, such as Cr, Al, Cu, W, Au, Ni, and Ag, can be usedas the supplementary electrode.

An insulating film 30 is formed on the first electrode 20. Anyinsulators, regardless of inorganic materials or organic materials, canbe used as the insulating film 30.

A barrier 70 is formed on the insulating film 30 to insulate intervalsof each second electrode (not shown).

As shown in FIG. 4, a shadow mask 60 is used to form each organicluminescence layer of R, G, and B and a common organic luminescencelayer of the same at a plurality of pixels on the transparent substrate10. The pixels are defined by a region crossed by the first and secondelectrodes.

FIG. 4 is a plane view of the shadow mask 60 in accordance of thepresent invention. The shadow mask 60 has a plurality of strip-shapedholes and a plurality of bridges 60-1 which connect the holes.

The transformation of the shadow mask 60 is prevented by the bridges60-1 which connect the holes.

Referring to FIG. 3A, one bridge 60-1 for each pixel is formed, but thebridge 60-1 is not necessarily formed at every pixel. In considerationof the transformation of the shadow mask 60, the bridge may be formedbetween every two or three pixels.

Preferably, the bridge 60-1 has its width ‘a’ and thickness ‘b’ in therange of 1˜1000 μm.

FIGS. 5A to 5C illustrate a detailed view of the part ‘A’ of the shadowmask of FIG. 4. The bridge 60-1 can be formed either on the same planeand at the same thickness as the shadow mask 60 as shown in FIG. 5A, oron a different plane and at a different thickness from the shadow mask60 as shown in FIG. 5B. Alternatively, the bridge 60-1 can also beformed on the same or different plane as or from the shadow mask at adifferent thickness from the shadow mask 60 as shown in FIG. 5C.

A common luminescence layer of R, G, and B (not shown) is deposited onthe transparent substrate 10 at a time using a blank mask which candeposit all the entire luminescence region.

Subsequently, each organic luminescence layer of R, G, and B isalternately arranged in rows at the pixel by three times aligning theshadow mask 60.

The common luminescence layer of R, G, and B may also be formed at eachpixel of R, G, and B using the shadow mask 60, not being deposited onthe entire luminescence region.

Subsequently, the second electrode (not shown) is formed by forming asecond electrode (Mg—Ag alloy, or Al, or other conductive materials)using the blank shadow mask.

Then, passivation layers (oxygen adsorption layer, moisture adsorptionlayer, and moisture-proof layer) are formed on the second electrode andencapsulation is carried out.

The full-color organic EL display device in accordance with the presentinvention has the following advantages.

By forming mask holes in the form of a bridge, the transformation anddroop of the shadow mask caused by the pulling strength is prevented.Thus, efficiency of the full-color organic EL display device ismaximized.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A mask for fabricating organic luminescence layer of an organicelectroluminescence display device, comprising: a plate having aplurality of holes, wherein the holes are formed as a striped shapeextending in a column direction; a first plurality of bridges crossingeach of the holes along a first row direction; and a second plurality ofbridges crossing each of the holes along a second row direction, whereineach of the bridges are formed on a different plane than the plate and athickness of each of the bridges is substantially equal to a thicknessof the plate, wherein lower surfaces of each of the bridges are on uppersurface of the plate and wherein the plurality of holes definedeposition areas on the organic electroluminescence display device onwhich material is to be deposited.
 2. The mask of claim 1, wherein thebridges have their width and thickness in the range of 1˜1000 μm.
 3. Amask for fabricating organic luminescence layer of an organicelectroluminescence display device, comprising: a plate having aplurality of holes each having a width, wherein the holes are formed asa striped shape extending in a column direction; a first plurality ofbridges crossing each of the holes along a first row direction; and asecond plurality of bridges crossing each of the holes along a secondrow direction, wherein each of the bridges are formed on a differentplane than the plate and a thickness of each of the bridges issubstantially equal to a thickness of the plate, wherein lower surfacesof the each of bridges are on upper surface of the plate and whereineach of the stripe-shaped holes is separated by a distance equal toabout twice the width of the holes.